diff --git a/bin/extract_vtfeatures.js b/bin/extract_vtfeatures.js
index 63d09684..62ad9ff9 100644
--- a/bin/extract_vtfeatures.js
+++ b/bin/extract_vtfeatures.js
@@ -359,7 +359,7 @@ function empty(ar) {
 }
 
 function* parseMultiLineGen(filename, s) {
-  if (!~s.indexOf('@vt:')) {
+  if (!s.includes('@vt:')) {
     return;
   }
   const lines = s.split('\n').map(el => el.trim().replace(/[*]/, '').replace(/\s/, ''));
@@ -413,7 +413,7 @@ function parseSingleLine(filename, s) {
   const line = s.trim();
   const match = line.match(REX_VT_LINE);
   if (match !== null) {
-    if (!~TYPES.indexOf(match[2])) {
+    if (!TYPES.includes(match[2])) {
       throw new Error(`unkown vt-command type "${match[2]}" specified in "${filename}"`);
     }
     return {
diff --git a/bin/install-addons.js b/bin/install-addons.js
index 83adea1f..99f0a0aa 100644
--- a/bin/install-addons.js
+++ b/bin/install-addons.js
@@ -25,7 +25,7 @@ if (fs.existsSync(addonsPath)) {
 
   // walk all addon folders
   fs.readdir(addonsPath, (err, files) => {
-    files.forEach(folder => {
+    for (const folder of files) {
       const addonPath = path.join(addonsPath, folder);
 
       // install only if there are dependencies listed
@@ -51,6 +51,6 @@ if (fs.existsSync(addonsPath)) {
       } else {
         console.log('Skipped', folder);
       }
-    });
+    }
   });
 }
diff --git a/bin/publish.js b/bin/publish.js
index fd0015d6..64336fdc 100644
--- a/bin/publish.js
+++ b/bin/publish.js
@@ -11,7 +11,7 @@ const path = require('path');
 // Setup auth
 fs.writeFileSync(`${process.env['HOME']}/.npmrc`, `//registry.npmjs.org/:_authToken=${process.env['NPM_AUTH_TOKEN']}`);
 
-const isDryRun = process.argv.indexOf('--dry') !== -1;
+const isDryRun = process.argv.includes('--dry');
 if (isDryRun) {
   console.log('Publish dry run');
 }
@@ -36,13 +36,13 @@ const addonPackageDirs = [
   path.resolve(__dirname, '../addons/xterm-addon-webgl')
 ];
 console.log(`Checking if addons need to be published`);
-addonPackageDirs.forEach(p => {
+for (const p of addonPackageDirs) {
   const addon = path.basename(p);
-  if (changedFiles.some(e => e.indexOf(addon) !== -1)) {
+  if (changedFiles.some(e => e.includes(addon))) {
     console.log(`Try publish ${addon}`);
     checkAndPublishPackage(p);
   }
-});
+}
 
 // Publish website if it's a stable release
 if (isStableRelease) {
@@ -54,7 +54,7 @@ function checkAndPublishPackage(packageDir) {
 
   // Determine if this is a stable or beta release
   const publishedVersions = getPublishedVersions(packageJson);
-  const isStableRelease = publishedVersions.indexOf(packageJson.version) === -1;
+  const isStableRelease = !publishedVersions.includes(packageJson.version);
 
   // Get the next version
   let nextVersion = isStableRelease ? packageJson.version : getNextBetaVersion(packageJson);
diff --git a/bin/test_api.js b/bin/test_api.js
index 7afb34bc..eb068b89 100644
--- a/bin/test_api.js
+++ b/bin/test_api.js
@@ -21,7 +21,7 @@ let flagArgs = [];
 
 if (process.argv.length > 2) {
   const args = process.argv.slice(2);
-  flagArgs = args.filter(e => e.startsWith('--')).map(arg => arg.split('=')).reduce((arr, val) => arr.concat([...val], []));
+  flagArgs = args.filter(e => e.startsWith('--')).map(arg => arg.split('=')).reduce((arr, val) => arr.concat(val.split(''), []));
   console.info(flagArgs);
   // ability to inject particular test files via
   // yarn test [testFileA testFileB ...]
diff --git a/bin/test_mousemodes.js b/bin/test_mousemodes.js
index 976a38e0..6a547ab1 100644
--- a/bin/test_mousemodes.js
+++ b/bin/test_mousemodes.js
@@ -88,19 +88,19 @@ function evalButtonCode(code) {
   if (code & 64) {
     button |= 4
   }
-  let actionS = 'press';
+  let action = 'press';
   let buttonS = reverseButtons[button];
   if (button === 3) {
     buttonS = '<none>';
-    actionS = 'release';
+    action = 'release';
   }
   if (move) {
-    actionS = 'move';
+    action = 'move';
   } else if (4 <= button && button <= 7) {
     buttonS = 'wheel';
-    actionS = button === 4 ? 'up' : button === 5 ? 'down' : button === 6 ? 'left' : 'right';
+    action = button === 4 ? 'up' : button === 5 ? 'down' : button === 6 ? 'left' : 'right';
   }
-  return {button: buttonS, action: actionS, modifier};
+  return {button: buttonS, action, modifier};
 }
 
 // protocols